Belt-tightener.



J. H. SBWALL. BELT TIGHTENER- APPLICATION FILED 1120.31, 1908.

Patented Feb. 6, 1912.

2 SHEETSSHEET 1.

J. H. SEWALL.

BELT TIGHTENER.

APPLICATION FILED DEC. 31, 1908.

Patented Feb. 6, 1912.

2 SHEETS-SHEET 2.

I'Iiil ///////////////////4\ Q //-Q- UNITED STATES PATENT OFFICE.

JAMES H. SEWALL, OF KEENE, NEW HAMPSHIRE, ASSIGNOR OF ONE-HALF T0 DANIELI). SEWALL, OF AUGUSTA, MAINE.

BELT-TIGHTENER.

Specification of Letters Patent.

Patented Feb. 6, 1912.

T 0 all whom it may concern:

Be it known that I, JAMES H. SEWALL, of Keene, in the county of Cheshireand State of New Hampshire, a citizen of the United States, haveinvented a new and useful Improvement in Belt-Tighteners, of which thefollowing is a full, clear, and exact description, reference being hadto the accompanying drawings, forming a part of this specification, inexplaining its nature.

My invention relates essentially to a means or device for regulating,taking up or compensating for any slack or variation in the tension of abelt connecting pulleys or similar parts.

The especial object of my invention is to provide such means or deviceas will be automatic in its operation and be operated by power inherentin the belt itself during the operation thereof without the use ofsprings or other auxiliary power or force inducing parts; and whichdevice also will operate irrespective of the direction in which the beltis moving.

My invention relates also to a means whereby the device aforementionedmay be made to increase the bearing surface of the belt-upon any pulleyin connection with which the device is used and be made also to providea frictional bearing surface or surfaces supplementing the frictionalbearing of the belt on the pulley, thereby diminishing the chance of thebelt slipping on the pulley without retarding the operation of the belt.

A further object of my invention is to provide a means or device of theaforesaid character applicable for use in connection with pulleys andconnecting belt or like parts used for the purpose of transmitting powerfrom the axle or running gear of a car to a dynamo generating anelectric current for lighting the car. A belt used under thesecircumstances is susceptible to considerable variation or tension owingto the movement of the axle and pulley thereon, from which the power istaken, relatively to the driven pulley on the axle of the armature ofthe dynamo. Such relative movement is occasioned not only by reason ofthe fact that the dynamo is aflixed to the truck yieldingly supportedwith respect to the axle of the car but also and more essentially forthe reason that when the brakes are applied to the car wheels theposition of their axle is considerably changed.

My invention can best be seen and understood by reference to thedrawings in which Figure 1 shows the device mainly in vertical crosssection. Fig. 2 shows the device in side elevation, and Fig. 3 is alongitudinal vertical section of the device.

In the drawings :1 represents a shaft which may be the axle connectingwith the two wheels (not shown) of a car. Aflixed to this shaft is apulley 2 which for purposes of illustration may be termed the drivingpulley.

3 represents a pulley affixed to a shaft 4- which may be the shaft forturning the armature of a dynamo (not shown). The pulley 3 for purposesof illustration may be termed the driven pulley. Connecting the pulleys2 and 3 is a belt 5. Pivotally mounted upon the shaft 4 is a swingingframe 6 having connected sides 7 spaced apart and in which are journaledto turn idler pulleys 8 and 9 auxiliary to the pulley 3 and cooperatingwith this pulley in the regulation and adjustment of the belt as willhereinafter be explained. The sides 7 pivotally connect with the shaft 4at points just adj acent to the respective ends of the pulley 3 so thatthe auxiliary pulleys borne by the frame will be maintained in properposition ;to cooperate with the belt. The two sides of the frame areeach pivotally secured to the shaft 4 by means of a projecting shoulder10 forming one portion of a box around the shaft 4, the other section ofthe box being formed by a cap 11 bolted to the box section 10. The twosides of the frame are further united by means of a cross bolt 12 andattaching nut. The two sides 7 are held properly spaced apart for thepulleys 8 and 9 to turn freely in andbet-ween them by means of hubs 13projecting laterally from the interiors of the respective sides 7 andmeeting in abutting ends, the length of the hubs being such as willdefine a proper spacing or separation of the two sides. In theconstruction shown, which is a preferred construction, the bolt 12passes through these two hubs which embrace the bolt in the manner ofsleeves. As the nut on the end of the bolt is tightened the abuttingends of the hubs will be brought tightly together which not only acts todefine the proper separated position of the two sides but also to braceand strengthen the entire structure of the frame.

As said before, the construction I have indicated is only a preferredconstruction which may well be varied. It presents, however, theadvantages of providing a proper mounting for the auxiliary pulleys andone which permits of these pulleys being simultaneously shifted or movedwith respect to the belt 5 upon the application of a force or pressuretending to move them. In other words, the'pulleys 8 and 9 maysimultaneously be shifted or moved in a direction transverse to the lineof centers of the pulleys 2 and 3 on an are around the pulley 3, theframe 6 causing the pulleys 8 and 9 to be moved in unison about the axisof the shaft 4:.

. Before referring to the particular disposition and adaptation of theauxiliary pulleys, attention is directed to the casing 14 secured to theframe and which may be so made and affixed as to cover not only thepulleys carried by the frame but also the pulley 3 with which theauxiliary pulleys cooperate.

In respect to the disposition and arrangement of the auxiliary pulleysin the frame 6, it may be said that the axis of these pulleys are eachpreferably the same distance from the axis of the pulley 3. Theauxiliary pulleys are also so located that each will present a bearingsurface acting to angularly flex or bend in different directions theoppositely moving portions 5 5 of the belt running between the pulleys 2and 3. I prefer also that the pulleys 8 and 9 shall he outside the belt.Accordingly to obtain the effect above noted it is necessary that thearrangement of the pulleys be such that the distance between thesurfaces thereof bearing against the belt should be less than thediameter of the pulley 3. lVith the auxiliary pulleys thus arranged anddisposed in respect to the belt and the pulleys 2 and 3, the belt as itturns, assuming that it is running in the direction indicated by thearrow, will pass off of the pulley 3, thence inwardly aroundthe'auxiliary pulley 8, thence outwardly around the pulley 2, thenceinwardly around the auxiliary pulley 9 and outwardly around the pulley 3to the point of beginning. Now with the belt moving in the directionindicated by the arrow, it is a fact that the portion 5 of the beltduring its operation will be maintained under a greater tension than itsoppositely moving portion 5, this difference of tension being occasionedby the pull of the driving pulley on the belt and the amount ofdifference in tension will vary depending upon the load on the drivenpulley 3. In consequence of there being an increased tension between theportions 5 and 5 of the belt the tendency will be for the portion 5 ofthe belt to bear harder against the auxiliary pulley 8 than the bearingof the portion 5 of the belt against the pulley 9. Accordingly theportion 5 of the belt bearing against the pulley 8 will act to move bothpulleys 8 and 9 from their normal positions, the pulleys yielding to theinfluence of the belt and the angles of flexure or bending of saidrespective portions of the belt produced by the respective pulleys willbecome changed, the angle in the portion 5 of the belt becoming moreobtuse as the angle in its portion T becomes more acute. The effect isthat although both auxiliary pulleys are moved an equal amount yet thepulley 9 in its changed position will act to take up more of the beltthan is let out by the pulley 8. The immediate effect of this is thatany undue tension in the portion 5 of the belt will be relieved and theslack occasioned by such relief immediately taken up or coinpensated forin the portion 5 thereby dist-ributing the strain evenly throughout theentire belt.

In the event of slack in the belt caused by the changed position of thepulley 2 or the pulley 3 or even that of both pulleys (for purposes ofillustration I have shown only a'changed position of the pulley 2), theimmediate effect is that the slack in the belt will be taken up. In suchcase the slack will not occur in the portion 5 of the belt which isbeing drawn off the pulley 3 onto the pulley 2 by reason of the drawingstrain exerted by the driving pulley, but the slack will occur in theportion 5" of the belt which is rendering otr the pulley 2 and drawingonto the pulley 3. Accordingly the tension in the portion 5 of the beltwill be maintained with the effect that this portion of the belt drawingagainst the pulley 8 will tend to move this pulley inasmuch as there isnothing to retard such movementand the movement of the pulley 8 togetherwith the pulley 9, which is a simultaneous movement, will continueuntil. the pulley 9 draws against the portion 5 of the belt, taking upthe slack therein. It is true that as the pulley 8 is moved the belt islet out, and though the pulley 9 is moved only an equal amount, yet thispulley will act to take up more of the belt in the portion 5 than is letout in the portion 5, thereby taking up the slack formed in the beltoccasioned as aforesaid. When the slack in the belt thustaken up iseliminated as by the restoration of the pulley 2 to its originalposition, the auxiliary pulleys will simply be drawn back by theswinging of the frame to their original positions where they act toregulate the normal running of the belt in the manner above explained.

The device will work equally as well whether the belt is moving in thedirection indicated or in a reverse direction. In case the belt moves ina direction reverse to that above noted the only difference in theaction from that above described is that the pulley 8 will act to takeup the slack in the belt instead of the pulley 9. It is evident alsothat the operation of the device is independent of the disposition ofthe device in respect to the driving or driven pulley. Usually thedevice is located to cooperate with the smaller pulley which in mostcases is the driven pulley.

Under some circumstances instead of the belt being slackened by achanged position of the pulleys around which it is rendering, either oneor both of these pulleys may be moved out extending the belt as it were.Such movement can be compensated for by making the belt so long thatwhen the pulleys are extended outwardly from their normal positions thebelt will be of suflicient length to permit of such movement.Accordingly when the pulleys are in their normal positions by reason ofthe relative slack in the belt so occasioned the auxiliary pul leys willbe turned to a position where this slack will be compensated for ortaken up by the formation of unequal angles of flexure in the respectiveportions of the belt. Then as the pulleys around which the belt isrendering are drawn out or extended the position of the slack adjustingdevice will be changed to vary the angles of flexure still further by anamount commensurate with the changed position of the belt.

In respect to that adaptation of my device whereby it may act torelatively increase the friction surface of the pulley (with which thedevice is cooperating), normally bearing against or presented to thebelt rendering over the same, and to supplement this friction surface byproviding in itself auxiliary friction surfaces engaging the beltthereby lessening the chance of the belt slipping on the pulley,attention is first directed to the fact that the auxiliary pulleys 8 and9, located as they are on the outside of the belt and flexing or bendingthe belt as they do, act to draw the belt around the pulley 3 with whichthe auxiliary pulleys are cooperating and so increase the frictionbearing of the belt on this pulley over that it would normally have onthe pulley. The auxiliary pulleys may also be made (as they preferablyare made in order to best obtain the present effect), of the same sizeas the driven pulley 3 with which they are cooperating. They may also begeared to the driven pulley, all of the pulleys being connected by gears15 arranged upon the ends of the set of pulleys 8, 8 and 9, these gearstaking the place of the usual flange on the ends of the pulleys whichact to guide and retain the belt. The effect of this is that the pulleyswill all rotate simultaneously in the direction the belt is moving asindicated by the arrows. Now the belt bears for a considerable distanceupon both auxiliary pulleys 8 and 9 and inasmuch as these pulleys canrotate only in unison with the pulley 3 with which they are cooperating,the surface of the pulleys 8 and 9 against which the belt frictionallybears accordingly supplements the surface of the pulley 3 against whichthe belt is frictionally bearing thereby lessening the chance of thebelt slipping on the pulley 3. Respecting this last phase of myinvention and in further reference to the size of the pulleys 8 and 9with respect to the pulley 3, whatever the size of the pulleys 8 and 9may be, it is desirable that the peripheral surfaces of all therespective pulleys run at the same rate of speed.

A further advantage of applicants in vention resides in the fact that inthe event of the belt slipping on the main pulley such action willimmediately be rectified by the tightening of the belt against the mainpulley. If the belt slips over the main pulley then the motion of theslipping belt will cause the auxiliary pulleys to rotate faster than themain pulley thereby causing them to turn around the main pulley andchange the, angles of flexure in the belt and so tighten it against themain pulley and prevent further slipping. In other words, by reason ofthe geared connection between the pulleys, if the belt slips theauxiliary pulleys will be rotatably moved by the slipping belt aroundthe main pulley to a position Where by reason of-the change in theangles of fiexure the belt will be made to draw hard against the mainpulley by the taking up of the belt.

Having thus fully described my invention, I claim and desire to secureby Letters Patent of the United States 1. The combination with a pair ofpulleys and a belt connecting said pulleys, of means automaticallycontrolled by the differences in tension in the respective portions ofthe belt for taking up variable slack therein, said means comprising apair of auxiliary pulleys normally forming angles of flexure in saidrespective portions, and movable means connecting said auxiliary pulleyswhereby they are moved in unison in a direction transverse to the lineof centers of said first-named pulleys by said differences in tension,thereby varying said angles of fiexure.

2. The combination with a pair of pulleys connecting said auxiliarypulleys whereby belt for taking up variable slack therein, said meanscomprising a pair of auxiliary pulleys normally forming angles offlexure in said respective portions, and means connecting said auxiliarypulleys and movable about a center in the axis of rotation of one ofsaid first-named pulleys whereby said auxiliary pulleys are moved inunison in a direction transverse to the line of centers of saidfirst-named pulleys by said differences in tension, thereby varying saidangles. of flexure.

3. The combination with a pair of pulleys and a belt connecting saidpulleys, of means automatically controlled by the differences in tensionin the respective portions of said belt fortaking up variable slacktherein, said means comprising a pair of auxiliary pulleys movable abouta common center and normally arranged to engage said belt and formangles of fiexure in said respective portions thereof at pointssubstantially the same distance removed from said center, and meanspivotally arranged to be movable about said center and connecting andcarrying said auxiliary pulleys whereby said auxiliary pulleys are.movable in unison in a direction around said center by said differencesin tension, thereby varying said angles of flexure.

4. The combination with and a belt connecting said pulleys, of meansautomatically controlled by the differences in tension in the respectiveportions of said belt for taking up variable slack therein, said meanscomprising a pair of auxiliary pulleys and movable means connecting andcarrying said auxiliary pulleys whereby they are moved in unison in adirection transverse to the line of centers of said first-named pulleysby said difierences in tension to normally form unequal angles offiexure in said portions of the belt.

5. The combination with a pulley and a belt running about said pulley,of a shaft to which said pulley is aflixed, a frame pivotally supportedfrom said shaft, said frame comprising sides spaced from one another andeach pivotally connecting with said shaft on either side of said pulley,hubs extending from the interior of said sides and meeting in abuttingedges for defining the separated position of said sides, means forsecuring said sides to one another, and auxila pair of pulleys iarypulleys carried by said frame to cooperate with said belt.

6. The combination with a pair of pulleys and a belt, connecting saidpulleys, of means automatically controlled by the differences in tensionin the respective portions of said belt for taking up variable slacktherein,said means comprising a set of auxiliary pulleys normallyforming angles of fiexure in said respective portions, movable meansthey are moved in unison in a direction,

transverse to the line of centers of said firstnamed pulleys by saiddifferences in tension, thereby varying said angles of flexure, the oneangle becoming more acute as the other becomes more obtuse, and meansconnecting said auxiliary pulleys with one of said first named pulleyswhereby all said pulleys may rotate in unison.

7. The combination with a pair of main pulleys and a belt connectingsaid pulleys, of a set of auxiliary pulleys, means for holding saidauxiliary pulleys in contact with said belt, and means connecting saidauxiliary pulleys with one of said main pulleys for rotation in unisontherewith, whereby the friction bearing of said belt against said mainpulley is supplemented by its bearing against said auxiliary pulleys.

8. The combination of a main pulley and a belt, of a set of auxiliarypulleys over which the belt renders as it passes onto and off said mainpulley, said auxiliary pulleys being movable to draw said belt aroundsaid main pulley in part, means for pivotally supporting said auxiliarypulley from the axis of said main pulley, and means connecting said mainand auxiliary pulleys, whereby they may rotate in unison.

9. The combination with a pair of main pulleys and a belt connectingsaid pulleys, of a set of auxiliary pulleys engaging said belt andadapted to flex the portions thereof in different angular directions,pivoted means for supporting said auxiliary pulleys and permittingbodily movement thereof to change the angles of flexure in said portionsof the belt, the one becoming more acute as the other becomes moreobtuse, and mechanism connecting said auxiliary pulleys for moving thesame around their pivotal support when said belt slips over one of saidmain pulleys.

10. The combination with a pair of main pulleys and a belt connectingsaid pulleys, of a set of auxiliary pulleys engaging said belt to flexthe portions thereof in dilferent angular directions, pivoted means forsupporting said auxiliary pulleys and permitting bodily movement thereofto change the angles of flexure in said portions of the belt, the onebecoming more acute as the other becomes more obtuse, and mechanismconnecting one of said main pulleys with an auxiliary pulley for movingsaid auxiliary pulley around said main pulley when said auxiliary pulleyis actuated by the slipping of said belt on said main pulley.

11. The combination with a pair of main pulleys and a belt connectingsaid pulleys, of a set of auxiliary pulleys engaging said belt to flexthe portions thereof in different angular directions, means forsupporting said auxiliary pulleys pivoted on an axis coincident with theaxis of one of said main pulleys and permitting bodily movement of mainpulley When said auxiliary pulleys are said auxiliary pulleys in adirection around actuated by the slipping of the belt on said 10 saidmain pulley to change the angles of main pulley;

fiexure in said portions of the belt, the one JAMES H. SEWALL. becomingmore acute as the other becomes more obtuse, and geared connections be-In the presence oftween said main and auxiliary pulleys for JOHN E. R.HAYEs,

moving said auxiliary pulleys around said M. E. FLAHERTY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

